U.S. patent application number 14/177093 was filed with the patent office on 2014-08-14 for chassis-excited antenna apparatus and methods.
The applicant listed for this patent is Pulse Finland OY. Invention is credited to Petteri Annamaa, Prasadh Ramachandran.
Application Number | 20140225787 14/177093 |
Document ID | / |
Family ID | 46636476 |
Filed Date | 2014-08-14 |
United States Patent
Application |
20140225787 |
Kind Code |
A1 |
Ramachandran; Prasadh ; et
al. |
August 14, 2014 |
CHASSIS-EXCITED ANTENNA APPARATUS AND METHODS
Abstract
A chassis-excited antenna apparatus, and methods of tuning and
utilizing the same. In one embodiment, a distributed loop antenna
configuration is used within a handheld mobile device (e.g.,
cellular telephone). The antenna comprises two radiating elements:
one configured to operate in a high-frequency band, and the other
in a low-frequency band. The two antenna elements are disposed on
different side surfaces of the metal chassis of the portable
device; e.g., on the opposing sides of the device enclosure. Each
antenna component comprises a radiator and an insulating cover. The
radiator is coupled to a device feed via a feed conductor and a
ground point. A portion of the feed conductor is disposed with the
radiator to facilitate forming of the coupled loop resonator
structure.
Inventors: |
Ramachandran; Prasadh;
(Kempele, FI) ; Annamaa; Petteri; (Oulunsalo,
FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Pulse Finland OY |
Kempele |
|
FI |
|
|
Family ID: |
46636476 |
Appl. No.: |
14/177093 |
Filed: |
February 10, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13026078 |
Feb 11, 2011 |
8648752 |
|
|
14177093 |
|
|
|
|
Current U.S.
Class: |
343/702 ;
343/700MS; 343/749; 343/867 |
Current CPC
Class: |
H01Q 7/00 20130101; H01Q
1/38 20130101; H01Q 1/50 20130101; H01Q 13/10 20130101; H01Q 21/28
20130101; H01Q 1/24 20130101; H01Q 9/42 20130101; H01Q 1/42
20130101; H01Q 1/22 20130101; H01Q 1/243 20130101 |
Class at
Publication: |
343/702 ;
343/867; 343/700.MS; 343/749 |
International
Class: |
H01Q 1/22 20060101
H01Q001/22; H01Q 1/50 20060101 H01Q001/50; H01Q 7/00 20060101
H01Q007/00 |
Claims
1.-30. (canceled)
31. A mobile communications device, comprising: an exterior housing
comprising a plurality of sides; an electronics assembly comprising
a ground and at least one feed port, the electronics assembly
substantially contained within the exterior housing; and an antenna
component comprising: a radiator element comprising first and
second surfaces, and configured to be disposed proximate to a first
side of the exterior housing; a feed conductor coupled to the at
least one feed port, and configured to couple to the radiator
element at a feed point; and a dielectric element disposed between
the first surface of the radiator element and the first side of the
exterior housing, the dielectric element operable to electrically
isolate at least a portion of the first surface of the radiator
element from the first side of the exterior housing.
32. The mobile communications device of claim 31, wherein: the
exterior housing comprises a substantially metallic structure; and
the antenna component comprises a first dimension and a second
dimension, and is configured to operate in a first frequency
band.
33. The mobile communications device of claim 32, further
comprising a dielectric substrate having a third dimension and a
fourth dimension, and configured to be disposed proximate the
second surface of the radiator element.
34. The mobile communications device of claim 33, wherein: a
projection of the dielectric substrate is equal to or larger than a
projection of the radiator element; and the radiator element is
electrically coupled to the ground via at least one ground
point.
35. The mobile communications device of claim 32, wherein at least
a portion of the feed conductor is arranged along a portion of the
first side of the exterior housing substantially parallel to the
first dimension of the antenna component such that the radiator
element, the portion of the feed conductor, and the portion of the
first side of the exterior housing form a coupled loop antenna
operable in the first frequency band.
36. The mobile communications device of claim 31, wherein: the
radiator element comprises a conductive structure comprising a
first portion and a second portion; and the second portion is
coupled to the feed point via a reactive circuit.
37. The mobile communications device of claim 36, wherein the
reactive circuit comprises a planar transmission line.
38. The mobile communications device of claim 36, wherein the
second portion further comprises a second reactive circuit
configured to adjust an electrical size of the radiator
element.
39. The mobile communications device of claim 38, wherein the
second reactive circuit comprises at least one of (i) an inductive
element, and (ii) a capacitive element.
40. The mobile communications device of claim 36, wherein the
conductive structure of the radiator element comprises a conductive
coating disposed on a dielectric substrate.
41. The mobile communications device of claim 32, wherein: the
substantially metallic structure comprises a sleeve like shape
having at least a first cavity; and the first side of the exterior
housing comprises a metal support element disposed within the first
cavity.
42. The mobile communications device of claim 32, wherein the
radiator element comprises a dielectric substrate configured to
have a conductive coating disposed thereon.
43. The mobile communications device of claim 31, wherein the
radiator element comprises a flex circuit.
44. The mobile communications device of claim 31, further
comprising a second antenna component configured to operate in a
second frequency band, the second antenna component comprising: a
second radiator element configured to have first and second
surfaces, and comprising a second ground point coupled to the
exterior housing, the second radiator element configured to be
disposed proximate to a second side of the exterior housing; a
second feed conductor coupled to the at least one feed port, and
configured to be coupled to the second radiator element at a second
feed point; and a second non-conductive cover disposed proximate
the second radiator element so as to substantially cover the second
radiator element.
45. The mobile communications device of claim 44, further
comprising a second dielectric element disposed between the first
surface of the second radiator element and the second side of the
exterior housing, the second dielectric element configured to
electrically isolate at least a portion of the first surface of the
second radiator element from the second side of the exterior
housing.
46. The mobile communications device of claim 45, wherein a second
coupled loop antenna structure is formed between at least a portion
of the exterior housing, the second radiator element, and at least
a portion of the second feed conductor.
47. The mobile communications device of claim 44, wherein the
second side of the exterior housing is opposite the first side of
the exterior housing.
48. An antenna apparatus for use in a portable communications
device, the device comprising a metal enclosure having a plurality
of sides, and substantially housing an electronics assembly
comprising a ground and at least one feed port, the antenna
apparatus comprising: a first antenna assembly configured to
operate in a first frequency band, the first antenna assembly
comprising a first radiator element and a first feed conductor
disposed along a first side of the metal enclosure; and a second
antenna assembly configured to operate in a second frequency band,
the second antenna assembly comprising a second radiator element
and a second feed conductor disposed along a second side of the
metal enclosure; wherein a first coupled loop antenna structure is
formed between at least a portion of the first side of the metal
enclosure, the first radiator element, and at least a portion of
the first feed conductor disposed along the first side of the metal
enclosure; and wherein a second coupled loop antenna structure is
formed between at least a portion of the second side of the metal
enclosure, the second radiator element, and at least a portion of
the second feed conductor disposed along the second side of the
metal enclosure.
49. The antenna apparatus of claim 48, wherein the first side of
the metal enclosure is arranged substantially opposite the second
side of the metal enclosure.
50. The antenna apparatus of claim 48, wherein: the first radiator
element further comprises a first ground point and a first feed
point, and a first non-conductive cover disposed proximate the
first radiator element so as to substantially cover the first
radiator element disposed along the first side of the metal
enclosure; and the first feed conductor is coupled to the first
feed point and to the at least one feed port.
51. The antenna apparatus of claim 50, wherein: the second radiator
element further comprises a second ground point and a second feed
point, and a second non-conductive cover disposed proximate the
second radiator element so as to substantially cover the second
radiator element disposed along the second side of the metal
enclosure; the second feed conductor is coupled to the second feed
point and to the at least one feed port; and the first and second
ground points are electrically coupled to the metal enclosure.
52. The antenna apparatus of claim 51, further comprising a first
dielectric element disposed between a first surface of the first
radiator element and the first side of the metal enclosure, the
first dielectric element configured to electrically isolate at
least a portion of the first surface of the first radiator element
from the first side of the metal enclosure.
53. The antenna apparatus of claim 52, further comprising a second
dielectric element disposed between a first surface of the second
radiator element and the second side of the metal enclosure, the
second dielectric element configured to electrically isolate at
least a portion of the first surface of the second radiator element
from the second side of the metal enclosure.
54. The antenna apparatus of claim 48, wherein the first frequency
band comprises a frequency band between 700 and 960 MHz and the
second frequency band comprised an upper frequency band.
55. The antenna apparatus of claim 54, wherein the upper frequency
band comprises a frequency band between 1710 and 2150 MHz.
56. The antenna apparatus of claim 54, wherein the upper frequency
band comprises a global positioning system (GPS) frequency
band.
57. The antenna apparatus of claim 48, wherein the metal enclosure
comprises a sleeve like shape having a first cavity and a second
cavity; and the first side comprises a first metal support element
disposed within the first cavity and configured to receive the
first radiator element; and the second side comprises a second
metal support element disposed within the second cavity and
configured to receive the second radiator element.
58. An antenna component for use in a mobile communications device,
the device comprising a metal chassis having a plurality of sides,
and substantially housing an electronics assembly comprising a
ground and at least one feed port, the antenna component
comprising: a dielectric substrate comprising: a first surface
disposed proximate a first side of the metal chassis; and a second
surface having a conductive coating disposed thereon, the
conductive coating shaped to form a radiator structure and
configured to form at least a portion of a ground plane, the
radiator structure comprising: a ground point configured to couple
the at least a portion of the ground plane to the ground of the
electronics assembly; a first portion; a second portion coupled to
the first portion; and a conductive element that extends form the
second portion to a feed point.
59. The antenna component of claim 58, further comprising one or
more non-conductive slots formed on each side of the conductive
element to isolate the conductive element from the first
portion.
60. The antenna component of claim 59, wherein the conductive
element forms a transmission line that extends from the second
portion into the first portion but substantially isolated from the
first portion by the one or more non-conductive slots.
61. The antenna component of claim 60, wherein the conductive
element electromagnetically couples the radiator structure to the
metal chassis.
62. The antenna component of claim 61, further comprising at least
one ground clearance area disposed substantially within a perimeter
of the dielectric substrate and configured to form part of a loop
structure.
63. The antenna component of claim 62, wherein the second portion
further comprises a lumped reactive circuit configured to adjust an
electrical size of the radiator structure.
64. The antenna component of claim 63, wherein the lumped reactive
circuit comprises at least one of (i) an inductive element, and/or
(ii) a capacitive element.
Description
PRIORITY CLAIM
[0001] This application is a continuation of and claims priority to
co-owned and co-pending U.S. patent application Ser. No. 13/026,078
of the same title, filed Feb. 11, 2011, and issuing as U.S. Pat.
No. 8,648,752, the contents of which is being incorporated herein
by reference in its entirety.
COPYRIGHT
[0002] A portion of the disclosure of this patent document contains
material that is subject to copyright protection. The copyright
owner has no objection to the facsimile reproduction by anyone of
the patent document or the patent disclosure, as it appears in the
Patent and Trademark Office patent files or records, but otherwise
reserves all copyright rights whatsoever.
FIELD OF THE INVENTION
[0003] The present invention relates generally to antenna apparatus
for use in electronic devices such as wireless or portable radio
devices, and more particularly in one exemplary aspect to a
chassis-excited antenna, and methods of tuning and utilizing the
same.
[0004] Description of Related Technology
[0005] Internal antennas are commonly found in most modern radio
devices, such as mobile computers, mobile phones, Blackberry.RTM.
devices, smartphones, personal digital assistants (PDAs), or other
personal communication devices (PCD). Typically, these antennas
comprise a planar radiating plane and a ground plane parallel
thereto, which are connected to each other by a short-circuit
conductor in order to achieve the matching of the antenna. The
structure is configured so that it functions as a resonator at the
desired operating frequency. It is also a common requirement that
the antenna operate in more than one frequency band (such as
dual-band, tri-band, or quad-band mobile phones), in which case two
or more resonators are used. Typically, these internal antennas are
located on a printed circuit board (PCB) of the radio device,
inside a plastic enclosure that permits propagation of radio
frequency waves to and from the antenna(s).
[0006] Recent advances in the development of affordable and
power-efficient display technologies for mobile applications (such
as liquid crystal displays (LCD), light-emitting diodes (LED)
displays, organic light emitting diodes (OLED), thin film
transistors (TFT), etc.) have resulted in a proliferation of mobile
devices featuring large displays, with screen sizes of up to 180 mm
(7 in) in some tablet computers and up to 500 mm (20 inches) in
some laptop computers.
[0007] Furthermore, current trends increase demands for thinner
mobile communications devices with large displays that are often
used for user input (touch screen). This in turn requires a rigid
structure to support the display assembly, particularly during the
touch-screen operation, so as to make the interface robust and
durable, and mitigate movement or deflection of the display. A
metal body or a metal frame is often utilized in order to provide a
better support for the display in the mobile communication
device.
[0008] The use of metal enclosures/chassis and smaller thickness of
the device enclosure create new challenges for radio frequency (RF)
antenna implementations. Typical antenna solutions (such as
monopole, PIFA antennas) require ground clearance area and
sufficient height from ground plane in order to operate efficiently
in multiple frequency bands. These antenna solutions are often
inadequate for the aforementioned thin devices with metal housings
and/or chassis, as the vertical distance required to separate the
radiator from the ground plane is no longer available.
Additionally, the metal body of the mobile device acts as an RF
shield and degrades antenna performance, particularly when the
antenna is required to operate in several frequency bands
[0009] Various methods are presently employed to attempt to improve
antenna operation in thin communication devices that utilize metal
housings and/or chassis, such as a slot antenna described in
EP1858112B1. This implementation requires fabrication of a slot
within the printed wired board (PWB) in proximity to the feed
point, as well as along the entire height of the device. For a
device having a larger display, slot location, that is required for
an optimal antenna operation, often interferes with device user
interface functionality (e.g. buttons, scroll wheel, etc),
therefore limiting device layout implementation flexibility
[0010] Additionally, metal housing must have openings in close
proximity to the slot on both sides of the PCB. To prevent
generation of cavity modes within the device, the openings are
typically connected using metal walls. All of these steps increase
device complexity and cost, and impede antenna matching to the
desired frequency bands.
[0011] Accordingly, there is a salient need for a wireless antenna
solution for e.g., a portable radio device with a small form factor
metal body and/or chassis that offers a lower cost and complexity
and provides for improved control of antenna resonance, and methods
of tuning and utilizing the same.
SUMMARY OF THE INVENTION
[0012] The present invention satisfies the foregoing needs by
providing, inter alia, a space-efficient multiband antenna
apparatus and methods of tuning and use.
[0013] In a first aspect of the invention, an antenna component for
use in a portable communications device is disclosed. In one
embodiment, the antenna component comprises: a radiator having a
first dimension and a second dimension, a first and second surface,
the radiator configured to be proximate to a first side of said
plurality of sides; a dielectric substrate having a third dimension
and a fourth dimension, and configured to be disposed proximate the
second surface; and a feed conductor configured to couple to the
radiator element at a feed point.
[0014] In one variant, the dielectric substrate is configured such
that its normal projection is equal or larger than a normal
projection of the radiator element. The radiator element is further
electrically coupled to the ground at a ground point. At least a
portion of the feed conductor is further arranged along the first
side substantially parallel to the first dimension; and the
radiator element, the at least a portion of the feed conductor, and
at least a portion of the first side form a coupled loop antenna
operable in a first frequency band.
[0015] In another variant, the antenna component further comprises
a dielectric element disposed between the radiator element and the
first side and configured to electrically isolate at least a
portion of the first side from the radiator element; e.g., a
dielectric substrate and a conductive coating disposed thereon, or
a flex circuit.
[0016] In another variant, the radiator element of the antenna
component comprises a conductive structure having a first portion
and a second portion. The second portion is coupled to the feed
point via a reactive circuit. The antenna component further
comprises a dielectric element disposed between the radiator
element and the first side and configured to electrically isolate
at least a portion of the first side from the radiator element. The
reactive circuit of the antenna component comprises e.g., a planar
transmission line.
[0017] In yet another variant, the radiator element comprises a
dielectric substrate, and a conductive coating disposed thereon;
and the conductive structure comprises the conductive coating.
[0018] In another embodiment, the antenna component comprises: a
dielectric substrate having a plurality of surfaces; a conductive
coating disposed on at least one surface of the substrate, the
conductive coating configured to form at least a portion of a
ground plane, the ground plane having a ground point; and a
radiator structure. In one variant, the radiator structure
comprises: a feed; a first portion, a second portion, a stripline
coupled from said second portion to said feed point; and a
plurality of non conductive slots isolating substantially
separating the strip line from the first portion; and at least one
ground clearance area disposed substantially within perimeter of
the surface. The ground point is further configured to couple the
at least a portion of the ground plane to a ground of a host
device. The second portion is coupled to the first portion via a
conductive element.
[0019] In another variant, the second portion of the antenna
component is further coupled to the first portion via a reactive
circuit. The reactive circuit comprises e.g., at least one of (i)
an inductive element, and/or (ii) a capacitive element.
[0020] In a second aspect of the invention, an antenna apparatus
for use in a portable communications device is disclosed. In one
embodiment, the antenna apparatus comprises: a first antenna
assembly configured to operate in a first frequency band, and a
second antenna assembly configured to operate in a second frequency
band. The first antenna assembly comprises a first radiator element
comprising a first ground point and a first feed point, and is
disposed along a first of the plurality of sides of the device
enclosure, a first feed conductor coupled to the first feed point
and to the at least one feed port of the device, and a first
non-conductive cover disposed proximate the first radiator so as to
substantially cover the first radiator. The second antenna assembly
comprises a second radiator element comprising a second ground
point and a second feed point, and is disposed along a second of
the plurality of sides the device enclosure; a second feed
conductor coupled to the second feed point and to a feed port of
the device, and a second non-conductive cover disposed proximate
the second radiator so as to substantially cover the second
radiator.
[0021] In one variant, the metal enclosure of the device is
electrically coupled to device ground, to the first ground point,
and to the second ground point. At least a portion of the first
feed cable is disposed along the first side thereby forming a first
coupled loop antenna structure between at least a portion of the
enclosure, the first radiator element, and the at least a portion
of the first feed cable. At least a portion of the second feed
cable is disposed along the second side thereby forming a second
coupled loop antenna structure between at least a portion of the
enclosure, the second radiator element, and the at least a portion
of the second feed cable.
[0022] In another variant, the first and second radiator elements
are disposed substantially between the first and second covers,
respectively, and the metal enclosure.
[0023] In yet another variant, the antenna apparatus further
comprises a dielectric element disposed between the radiator
element and the first side and configured to electrically isolate
at least a portion of the first side from the radiator element.
[0024] In another variant the first and the second radiator
elements of the antenna are disposed substantially between the
first and second covers, respectively, and the metal enclosure.
[0025] In yet another variant, the first and the second antenna
elements are disposed on opposing surfaces of the device enclosure.
In another variant, the first and the second antenna elements are
disposed on adjacent sizes of the device enclosure.
[0026] In another embodiment of the antenna apparatus, the first
frequency band of the antenna comprises a frequency band between
700 and 960 MHz, and the second frequency band comprised an upper
frequency band.
[0027] In one variant, the upper frequency band comprises frequency
band between 1710 and 2150 MHz. In another variant, the upper
frequency band comprises a global positioning system (GPS)
frequency band.
[0028] In another variant, the portable device comprises a single
feed port.
[0029] In yet another variant, the device enclosure is fabricated
to form a sleeve like shape having a first cavity and a second
cavity. A first metal support structure is disposed within the
first cavity and configured to receive the first radiator element.
A second metal support structure is disposed within the second
cavity and configured to receive the second radiator element.
[0030] In a third aspect of the invention, a mobile communications
device is disclosed. In one embodiment, the mobile communications
device comprises: a substantially metallic exterior housing
comprising a plurality of sides; an electronics assembly contained
substantially therein and comprising a ground and at least one feed
port; and a first antenna assembly configured to operate in a first
frequency band. In one variant, the first assembly comprises: (i) a
first radiator element comprising a first ground point and a first
feed point, and disposed along a first of the plurality of sides; a
first feed conductor coupled to the first feed point and to the at
least one feed port; and a first non-conductive cover disposed
proximate the first radiator so as to substantially cover the first
radiator; and (ii) a second antenna assembly configured to operate
in a second frequency band, the second assembly comprising: a
second radiator element comprising a second ground point and a
second feed point, disposed along a second of the plurality of
sides; a second feed conductor coupled to the second feed point and
to a feed port; and a second non-conductive cover disposed
proximate the second radiator so as to substantially cover the
second radiator. The first ground point and the second ground point
are electrically coupled to the metal housing. A first coupled loop
resonance structure is formed between at least a portion of the
housing, the first radiator, and at least a portion of the first
feed cable. A second coupled loop resonance structure is formed
between at least a portion of the housing, the second radiator, and
at least a portion of the second feed cable.
[0031] In a fourth aspect of the invention, a method of operating
an antenna apparatus is disclosed.
[0032] In a fifth aspect of the invention, a method of tuning an
antenna apparatus is disclosed.
[0033] In a sixth aspect of the invention, a method of testing an
antenna apparatus is disclosed.
[0034] In a seventh aspect of the invention, a method of operating
a mobile device is disclosed.
[0035] In an eighth aspect, a mobile communications device is
disclosed. In one embodiment, the mobile communications device
includes an exterior housing having a plurality of sides; an
electronics assembly having a ground and at least one feed port,
and which is further configured to be substantially contained
within the exterior housing; and an antenna component.
[0036] In one variant, the antenna component includes a radiator
element having first and second surfaces, and is further configured
to be disposed proximate to a first side of the housing. A feed
conductor is coupled to the at least one feed port, and configured
to couple to the radiator element at a feed point. A dielectric
element is disposed between the first surface of the radiator
element and the first side of the housing, the dielectric element
configured to electrically isolate at least a portion of the first
surface of the radiator element from the first side of the
housing.
[0037] In a ninth aspect, an antenna apparatus for use in a
portable communications device is disclosed. In one embodiment, the
portable communications device includes a metal enclosure having a
plurality of sides, and that substantially houses an electronics
assembly having a ground and a feed port.
[0038] In one variant, the antenna apparatus includes: a first
antenna assembly configured to operate in a first frequency band
and having a first radiator element and a first feed conductor
disposed along a first side of the metal enclosure; and a second
antenna assembly configured to operate in a second frequency band
and having a second radiator element and a second feed conductor
disposed along a second side of the metal enclosure. A first
coupled loop antenna structure is formed between at least a portion
of the first side of the metal enclosure, the first radiator
element, and at least a portion of the first feed conductor
disposed along the first side of the metal enclosure. A second
coupled loop antenna structure is formed between at least a portion
of the second side of the metal enclosure, the second radiator
element, and at least a portion of the second feed conductor
disposed along the second side of the metal enclosure.
[0039] In a tenth aspect, an antenna component for use in a mobile
communications device is disclosed. In one embodiment, the mobile
communication device includes a metal chassis having a plurality of
sides that substantially houses an electronics assembly that
includes a ground and at least one feed port. In a first variant,
the antenna component includes a dielectric substrate having a
first surface disposed proximate a first side of the metal chassis,
and a second surface having a conductive coating disposed thereon,
the conductive coating being shaped so as to form a radiator
structure and configured to form at least a portion of a ground
plane. The radiator structure comprises a ground point configured
to couple a portion of the ground plane to the ground of the
electronics assembly, a first portion, a second portion coupled to
the first portion, and a conductive element that extends form the
second portion to a feed point.
[0040] Further features of the present invention, its nature and
various advantages will be more apparent from the accompanying
drawings and the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] The features, objectives, and advantages of the invention
will become more apparent from the detailed description set forth
below when taken in conjunction with the drawings, wherein:
[0042] FIG. 1 is a perspective view diagram detailing the
configuration of a first embodiment of an antenna assembly of the
invention.
[0043] FIG. 1A is a perspective view diagram detailing the
electrical configuration of the antenna radiator of the embodiment
of FIG. 1.
[0044] FIG. 1B is a perspective view diagram detailing the isolator
structure for the antenna radiator of the embodiment of FIG.
1A.
[0045] FIG. 1C is a perspective view diagram showing an interior
view of a device enclosure, showing the antenna assembly of the
embodiment of FIG. 1A installed therein.
[0046] FIG. 1D is an elevation view diagram of a device enclosure
showing the antenna assembly of the embodiment of FIG. 1A installed
therein.
[0047] FIG. 1E is an elevation view illustration detailing the
configuration of a second embodiment of the antenna assembly of the
invention.
[0048] FIG. 2A is an isometric view of a mobile communications
device configured in accordance with a first embodiment of the
present invention.
[0049] FIG. 2B is an isometric view of a mobile communications
device configured in accordance with a second embodiment of the
present invention.
[0050] FIG. 2C is an isometric view of a mobile communications
device configured in accordance with a third embodiment of the
present invention.
[0051] FIG. 3 is a plot of measured free space input return loss
for the exemplary lower-band and upper-band antenna elements
configured in accordance with the embodiment of FIG. 2C.
[0052] FIG. 4 is a plot of measured total efficiency for the
exemplary lower-band and upper-band antenna elements configured in
accordance with the embodiment of FIG. 2C.
[0053] All Figures disclosed herein are .COPYRGT. Copyright 2011
Pulse Finland Oy. All rights reserved.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0054] Reference is now made to the drawings wherein like numerals
refer to like parts throughout.
[0055] As used herein, the terms "antenna," "antenna system,"
"antenna assembly", and "multi-band antenna" refer without
limitation to any system that incorporates a single element,
multiple elements, or one or more arrays of elements that
receive/transmit and/or propagate one or more frequency bands of
electromagnetic radiation. The radiation may be of numerous types,
e.g., microwave, millimeter wave, radio frequency, digital
modulated, analog, analog/digital encoded, digitally encoded
millimeter wave energy, or the like. The energy may be transmitted
from location to another location, using, or more repeater links,
and one or more locations may be mobile, stationary, or fixed to a
location on earth such as a base station.
[0056] As used herein, the terms "board" and "substrate" refer
generally and without limitation to any substantially planar or
curved surface or component upon which other components can be
disposed. For example, a substrate may comprise a single or
multi-layered printed circuit board (e.g., FR4), a semi-conductive
die or wafer, or even a surface of a housing or other device
component, and may be substantially rigid or alternatively at least
somewhat flexible.
[0057] The terms "frequency range", "frequency band", and
"frequency domain" refer without limitation to any frequency range
for communicating signals. Such signals may be communicated
pursuant to one or more standards or wireless air interfaces.
[0058] The terms "near field communication", "NFC", and "proximity
communications", refer without limitation to a short-range high
frequency wireless communication technology which enables the
exchange of data between devices over short distances such as
described by ISO/IEC 18092/ECMA-340 standard and/or ISO/ELEC 14443
proximity-card standard.
[0059] As used herein, the terms "portable device", "mobile
computing device", "client device", "portable computing device",
and "end user device" include, but are not limited to, personal
computers (PCs) and minicomputers, whether desktop, laptop, or
otherwise, set-top boxes, personal digital assistants (PDAs),
handheld computers, personal communicators, tablet computers,
portable navigation aids, J2ME equipped devices, cellular
telephones, smartphones, personal integrated communication or
entertainment devices, or literally any other device capable of
interchanging data with a network or another device.
[0060] Furthermore, as used herein, the terms "radiator,"
"radiating plane," and "radiating element" refer without limitation
to an element that can function as part of a system that receives
and/or transmits radio-frequency electromagnetic radiation; e.g.,
an antenna.
[0061] The terms "RF feed," "feed," "feed conductor," and "feed
network" refer without limitation to any energy conductor and
coupling element(s) that can transfer energy, transform impedance,
enhance performance characteristics, and conform impedance
properties between an incoming/outgoing RF energy signals to that
of one or more connective elements, such as for example a
radiator.
[0062] As used herein, the terms "top", "bottom", "side", "up",
"down", "left", "right", and the like merely connote a relative
position or geometry of one component to another, and in no way
connote an absolute frame of reference or any required orientation.
For example, a "top" portion of a component may actually reside
below a "bottom" portion when the component is mounted to another
device (e.g., to the underside of a PCB).
[0063] As used herein, the term "wireless" means any wireless
signal, data, communication, or other interface including without
limitation Wi-Fi, Bluetooth, 3G (e.g., 3GPP, 3GPP2, and UMTS),
HSDPA/HSUPA, TDMA, CDMA (e.g., IS-95A, WCDMA, etc.), FESS, DSSS,
GSM, PAN/802.15, WiMAX (802.16), 802.20, narrowband/FDMA, OFDM,
PCS/DCS, Long Term Evolution (LTE) or LTE-Advanced (LTE-A), analog
cellular, CDPD, satellite systems such as GPS, millimeter wave or
microwave systems, optical, acoustic, and infrared (i.e.,
IrDA).
Overview
[0064] The present invention provides, in one salient aspect, an
antenna apparatus for use in a mobile radio device which
advantageously provides reduced size and cost, and improved antenna
performance. In one embodiment, the mobile radio device includes
two separate antenna assemblies located on the opposing sides of
the device: i.e., (i) on the top and bottom sides; or (ii) on the
left and right sides. In another embodiment, two antenna assemblies
are placed on the adjacent sides, e.g., one element on a top or
bottom side, and the other on a left or the right side.
[0065] Each antenna assembly of the exemplary embodiment includes a
radiator element that is coupled to the metal portion of the mobile
device housing (e.g., side surface). The radiator element is
mounted for example directly on the metal enclosure side, or
alternatively on an intermediate metal carrier (antenna support
element), that is in turn fitted within the mobile device metal
enclosure. To reduce potentially adverse influences during use
under diverse operating conditions, e.g., hand usage scenario, a
dielectric cover is fitted against the radiator top surface,
thereby insulating the antenna from the outside elements.
[0066] In one embodiment, a single multi-feed transceiver is
configured to provide feed to both antenna assemblies. Each antenna
may utilize a separate feed; each antenna radiator element directly
is coupled to a separate feed port of the mobile radio device
electronics via a separate feed conductor. This, inter alia,
enables operation of each antenna element in a separate frequency
band (e.g., a lower band and an upper band). Advantageously,
antenna coupling to the device electronics is much simplified, as
each antenna element requires only a single feed and a single
ground point connections. The phone chassis acts as a common ground
plane for both antennas.
[0067] In one implementation, the feed conductor comprises a
coaxial cable that is routed through an opening in the mobile
device housing. A portion of the feed cable is routed along lateral
dimension of the antenna radiator from the opening point to the
feed point on the radiator. This section of the feed conductor, in
conjunction with the antenna radiator element, forms the loop
antenna, which is coupled to the metallic chassis and hence
referred to as the "coupled loop antenna".
[0068] In one variant, one of the antenna assemblies is configured
to provide near-field communication functionality to enables the
exchange of data between the mobile device and another device or
reader (e.g., during device authentication, payment transaction,
etc.).
[0069] In another variant, two or more antennas configured in
accordance with the principles of the present invention are
configured to operate in the same frequency band, thus providing
diversity for multiple antenna applications (such as e.g., Multiple
In Multiple Out (MIMO), Multiple In Single Out (MISO), etc.).
[0070] In yet another variant, a single-feed antenna is configured
to operate in multiple frequency bands.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0071] Detailed descriptions of the various embodiments and
variants of the apparatus and methods of the invention are now
provided. While primarily discussed in the context of mobile
devices, the various apparatus and methodologies discussed herein
are not so limited. In fact, many of the apparatus and
methodologies described herein are useful in any number of complex
antennas, whether associated with mobile or fixed devices that can
benefit from the coupled loop chassis excited antenna methodologies
and apparatus described herein.
Exemplary Antenna Apparatus
[0072] Referring now to FIGS. 1 through 2C, exemplary embodiments
of the radio antenna apparatus of the invention are described in
detail.
[0073] It will be appreciated that while these exemplary
embodiments of the antenna apparatus of the invention are
implemented using a coupled loop chassis excited antenna (selected
in these embodiments for their desirable attributes and
performance), the invention is in no way limited to the loop
antenna configurations, and in fact can be implemented using other
technologies, such as patch or microstrip antennas.
[0074] One exemplary embodiment 100 of an antenna component for use
in a mobile radio device is presented in FIG. 1, showing an end
portion of the mobile device housing 102. The housing 102 (also
referred to as metal chassis or enclosure) is fabricated from a
metal or alloy (such as aluminum alloy) and is configured to
support a display element 104. In one variant, the housing 102
comprises a sleeve-type form, and is manufactured by extrusion. In
another variant, the chassis 102 comprises a metal frame structure
with an opening to accommodate the display 104. A variety of other
manufacturing methods may be used consistent with the invention
including, but not limited to, stamping, milling, and casting.
[0075] In one embodiment, the display 104 comprises a display-only
device configured only to display content or data. In another
embodiment, the display 104 is a touch screen display (e.g.,
capacitive or other technology) that allows for user input into the
device via the display 104. The display 104 may comprise, for
example, a liquid crystal display (LCD), light-emitting diode (LED)
display, organic light emitting diode (OLED) display, or TFT-based
device. It is appreciated by those skilled in the art that
methodologies of the present invention are equally applicable to
any future display technology, provided the display module is
generally mechanically compatible with configurations such as those
described in FIG. 1-FIG. 2C.
[0076] The antenna assembly of the embodiment of FIG. 1 further
comprises a rectangular radiator element 108 configured to be
fitted against a side surface 106 of the enclosure 102. The side
106 can be any of the top, bottom, left, right, front, or back
surfaces of the mobile radio device. Typically, modern portable
devices are manufactured such that their thickness 111 is much
smaller than the length or the width of the device housing. As a
result, the radiator element of the illustrated embodiment is
fabricated to have an elongated shape such that the length 110 is
greater than the width 112, when disposed along a side surface
(e.g., left, right, top, bottom).
[0077] To access the device feed port, an opening is fabricated in
the device enclosure. In the embodiment shown in FIG. 1, the
opening 114 extends through the side surface 106 and serves to pass
through a feed conductor 116 from a feed engine that is a part of
the device RF section (not shown), located on the inside of the
device. Alternatively, the opening is fabricated proximate to the
radiator feed point as described in detail below.
[0078] The antenna assembly of FIG. 1 further comprises a
dielectric antenna cover 118 that is installed directly above the
radiator element 108. The cover 118 is configured to provide
electrical insulation for the radiator from the outside
environment, particularly to prevent direct contact between a user
hand and the radiator during device use (which is often detrimental
to antenna operation). The cover 118 is fabricated from any
suitable dielectric material (e.g. plastic or glass). The cover 118
is attached by a variety of suitable means: adhesive, press-fit,
snap-in with support of additional retaining members as described
below.
[0079] In one embodiment, the cover 118 is fabricated from a
durable oxide or glass (e.g. Zirconium dioxide ZrO.sub.2, (also
referred to as "zirconia"), or Gorilla.RTM. Glass, manufactured by
Dow Corning) and is welded (such as via a ultrasonic-welding (USW)
technique) onto the device body. Other attachment methods may be
used including but not limited to adhesive, snap-fit, press-fit,
heat staking, etc.
[0080] In a different embodiment (not shown), the cover comprises a
non-conductive film, or non-conductive paint bonded onto one or
more exterior surfaces of the radiator element(s).
[0081] The detailed structure of an exemplary embodiment 120 of
radiator element 108 configured for mounting in a radio device is
presented in FIG. 1A. The radiator element 108 comprises a
conductive coating 129 disposed on a rigid substrate 141, such as a
PCB fabricated from a dielectric material (e.g., FR-4). Other
suitable materials, such as glass, ceramic, air are useable as
well. In one variant, a conductive layer is disposed on the
opposing surface of the substrate, thereby forming a portion of a
ground plane. In another implementation, the radiator element is
fabricated as a flex circuit (either a single-sided, or
double-sided) that is mounted on a rigid support element.
[0082] The conductive coating 129 is shaped to form a radiator
structure 130, which includes a first portion 122 and a second
portion 124, and is coupled to the feed conductor 116 at a feed
point 126. The second portion 124 is coupled to the feed point 126
via a conductive element 128, which acts as a transmission line
coupling antenna radiator to chassis modes.
[0083] The first portion 122 and the second portion 124 are
connected via a coupling element 125. In the exemplary embodiment
of FIG. 1A, the transmission line element 128 is configured to form
a finger-like projection into the first portion 122, thereby
forming two narrow slots 131, 133, one on each side of the
transmission line 128. The radiator 108 further includes a several
ground clearance portions (135, 137, 139), which are used to form a
loop structure and to tune the antenna to desired specifications
(e.g., frequency, bandwidth, etc).
[0084] The feed conductor 116 of exemplary embodiment of FIG. 1A is
a coaxial cable, comprising a center conductor 140, connected to
the feed point 126, a shield 142, and an exterior insulator 146. In
the embodiment of FIG. 1A, a portion of the feed conductor 116 is
routed lengthwise along the radiator PCB 108.
[0085] The shield 148 is connected to the radiator ground plane 129
at one or more locations 148, as shown in FIG. 1A. The other end of
the feed conductor 116 is connected to an appropriate feed port
(not shown) of the RF section of the device electronics. In one
variant this connection is effected via a radio frequency
connector.
[0086] In one embodiment, a lumped reactive component 152 (e.g.
inductive L or capacitive C) is coupled across the second portion
124 in order to adjust radiator electrical length. Many suitable
capacitor configurations are useable in the embodiment 120,
including but not limited to, a single or multiple discrete
capacitors (e.g., plastic film, mica, glass, or paper), or chip
capacitors. Likewise, myriad inductor configurations (e.g., air
coil, straight wire conductor, or toroid core) may be used with the
invention.
[0087] The radiating element 108 further comprises a ground point
136 that is configured to couple the radiating element 108 to the
device ground (e.g., housing/chassis). In one variant, the
radiating element 108 is affixed to the device via a conductive
sponge at the ground coupling point 136 and to the feed cable via a
solder joint at the feed point 126. In another variant, both above
connections are effected via solder joints. In yet another variant,
both connections are effected via a conductive sponge. Other
electrical coupling methods are useable with embodiments of the
invention including, but not limited to, c-clip, pogo pin, etc.
Additionally, a suitable adhesive or mechanical retaining means
(e.g., snap fit) may be used if desired to affix the radiating
element to the device housing.
[0088] In one exemplary implementation, the radiator element is
approximately 10 mm (0.3 in) in width and 50 mm (2 in) in length.
It will be appreciated by those skilled in the art that the above
antenna sizes are exemplary and are adjusted based on the actual
size of the device and its operating band. In one variant, the
electrical size of the antenna is adjusted by the use of a lumped
reactive component 152.
[0089] Referring now to FIGS. 1B through 1D, the details of
installing one or more antenna radiating elements 108 of the
embodiment of FIG. 1A into a portable device are presented. At step
154 shown in FIG. 1B, in order to ensure that radiator is coupled
to ground only at the desired location (e.g. ground point 136), a
dielectric screen 156 is placed against the radiating element 108
to electrically isolate the conductive structure 140 and the feed
point from the device metal enclosure/chassis 102. The dielectric
screen 156 comprises an opening 158 that corresponds to the
location and the size of the ground point 136, and is configured to
permit electrical contact between the ground point and the metal
chassis. A similar opening (not shown) is fabricates at the
location of the feed point. The gap created by the insulating
material prevents undesirable short circuits between the radiator
conductive structure 140 and the metal enclosure. In one variant,
the dielectric screen comprises a plastic film or non-conducting
spray, although it will be recognized by those of ordinary skill
given the present disclosure that other materials may be used with
equal success.
[0090] FIG. 1C shows an interior view of the radiating element 108
assembly installed into the housing 102. At step 160 the radiating
element is mounted against the housing side 106, with the
dielectric screen 156 fitted in-between. A channel or a groove 162
is fabricated in the side 106. The groove 162 is configured to
recess the conductor flush with the outer surface of the
enclosure/chassis, while permitting access to the radiator feed
point. This configuration decreases the gap between the radiator
element 108 and the housing side 106, thereby advantageously
reducing thickness of the antenna assembly. As mentioned above, a
suitable adhesive or mechanical retaining means (e.g., snap fit)
may be used if desired to affix the radiating element to the device
housing.
[0091] FIG. 1D shows an exterior view of the radiating element 108
assembly installed into the housing 102. At step 166 the radiating
element 108 is mounted against the housing side 106, with the
dielectric screen 156 fitted in between. FIG. 1D reveals the
conductive coating 143 forming a portion of the ground plane of the
radiating element, described above with respect to FIG. 1A. The
conductive coating 143 features a ground clearance element 168
approximately corresponding to the location and the size of the
ground clearance elements 135, 137 and the second portion 124 of
the radiator, disposed on the opposite side of the radiator element
108.
[0092] The exemplary antenna radiator illustrated in FIG. 1A
through 1D, uses the radiator structure that is configured to form
a coupled loop chassis excited resonator. The feed configuration
described above, wherein a portion of the feed conductor is routed
along the dimension 110 of the radiator, cooperates to form the
coupled loop resonator. A small gap between the loop antenna and
the chassis facilitates electromagnetic coupling between the
antenna radiator and the chassis. At least a portion of the metal
chassis 102 forms a part of an antenna resonance structure, thereby
improving antenna performance (particularly efficiency and
bandwidth). In one variant, the gap is on the order of 0.1 mm,
although other values may be used depending on the application.
[0093] The transmission line 128 forms a part of loop resonator and
helps in coupling the chassis modes. The length of the transmission
line controls coupling and feed efficiency including, e.g., how
efficiently the feed energy is transferred to the housing/chassis.
The optimal length of the transmission line is determined based, at
least in part on, the frequency of operation: e.g., the required
length of transmission line for operating band at approximately 1
GHz is twice the length of the transmission line required for the
antenna operating at approximately 2 GHz band.
[0094] The use of a single point grounding configuration of the
radiator to the metal enclosure/chassis (at the ground point 136)
facilitates formation of a chassis excited antenna structure that
is efficient, simple to manufacture, and is lower in cost compared
to the existing solutions (such as conventional inverted planar
inverted-F (FIFA) or monopole antennas). Additionally, when using a
planar configuration of the loop antenna, the thickness of the
portable communication device may be reduced substantially, which
often critical for satisfying consumer demand for more compact
communication devices.
[0095] Returning now to FIGS. 1A-1D, the ground point of the
radiator 108 is coupled directly to the metal housing (chassis)
that is in turn is coupled to ground of the mobile device RF
section (not shown). The location of the grounding point is
determined based on the antenna design parameters such as dimension
of the antenna loop element, and desired frequency band of
operation. The antenna resonant frequency is further a function of
the device dimension. Therefore, the electrical size of the loop
antenna (and hence the location of the grounding point) depends on
the placement of the loop. In one variant, the electrical size of
the loop PCB is about 50 mm for the lower band radiator (and is
located on the bottom side of the device enclosure), and about 30
mm for the upper band radiator (and is located on the top side of
the device enclosure). It is noted that positioning of the antenna
radiators along the longer sides of the housing (e.g., left side
and right side) produces loop of a larger electrical size.
Therefore, the dimension(s) of the loop may need to be adjusted
accordingly in order to match the desired frequency band of
operation
[0096] The length of the feed conductor is determined by a variety
of design parameters for a specific device (e.g., enclosure
dimensions, operating frequency band, etc.). In the exemplary
embodiment of FIG. 1A, the feed conductor 116 is approximately 50
mm (2 in) in length, and it is adjusted according to device
dimension(s), location of RF electronics section (on the main PCB)
and antenna dimension(s) and placement.
[0097] The antenna configuration described above with respect to
FIGS. 1-1D allows construction of an antenna that results in a very
small space used within the device size: in effect, a `zero-volume`
antenna. Such small volume antennas advantageously facilitate
antenna placement in various locations on the device chassis, and
expand the number of possible locations and orientations within the
device. Additionally, the use of the chassis coupling to aid
antenna excitation allows modifying the size of loop antenna
element required to support a particular frequency band.
[0098] Antenna performance is improved in the illustrated
embodiments (compared to the existing solutions) largely because
the radiator element(s) is/are placed outside the metallic chassis,
while still being coupled to the chassis.
[0099] The resonant frequency of the antenna is controlled by (i)
altering the size of the loop (either by increasing/decreasing the
length of the radiator, or by adding series capacitor/inductor);
and/or (ii) the coupling distance between the antenna and the
metallic chassis.
[0100] The placement of the antenna is chosen based on the device
specification, and accordingly the size of the loop is adjusted in
accordance with antenna requirements.
[0101] In the exemplary implementation illustrated in FIGS. 1A-1D
the radiating structure 130 and the ground point 138 are position
such that both faces the device enclosure/chassis. It is recognized
by those skilled in the art that other implementations are
suitable, such as one or both elements 130, 138 facing outwards
towards the cover 118. When the radiator structure 130 faces
outwards from the device enclosure, a matching hole is fabricated
in the substrate 141 to permit access to the feed center conductor
140. In one variation, the ground point 136 is placed on the ground
plane 143, instead of the ground plane 129.
[0102] FIG. 1E shows another embodiment of the antenna assembly of
the invention that is specifically configured to fit into a top or
a bottom side 184 of the portable device housing 188. In this
embodiment, the housing comprises a sleeve-like shape (e.g., with
the top 184 and the bottom sides open). A metal support element 176
is used to mount the antenna radiator element 180.
[0103] The implementation of FIG. 1E provides a fully metallic
chassis, and ensures rigidity of the device. In one variant, the
enclosure and the support element are manufactured from the same
material (e.g., aluminum alloy), thus simplifying manufacturing,
reducing cost and allowing to achieve a seamless structure for the
enclosure via decorative post processing processes.
[0104] In an alternative embodiment (e.g., as shown above in FIGS.
1C and 1D), the device housing comprises a metal enclosure with
closed vertical sides (e.g., right, left, top and bottom),
therefore, not requiring additional support elements, such as the
support element 168 of FIG. 1D.
[0105] The device display (not shown) is configured to fit within
the cavity 192 formed on the upper surface of the device housing.
An antenna cover 178 is disposed above the radiator element 180 so
as to provide isolation from the exterior influences.
[0106] The support element 176 is formed to fit precisely into the
opening 184 of the housing and is attached to the housing via any
suitable means including for example press fit, micro-welding, or
fasteners (e.g. screws, rivets, etc.), or even suitable adhesives.
The exterior surface 175 of the support element 176 is shaped to
receive the antenna radiator 180. The support element 178 further
comprises an opening 194 that is designed to pass through the feed
conductor 172. The feed conductor 172 is connected to the PCB 189
of the portable device and to the feed point (not shown) of the
antenna radiator element 180.
[0107] In one embodiment, the feed conductor, the radiator
structure, and the ground coupling arrangement are configured
similarly to the embodiments described above with respect to FIGS.
1A-1B.
[0108] In one variant, a portion of the feed conductor length is
routed lengthwise along the dimension 174 of the antenna support
element 176: e.g., along an interior surface of the element 176, or
along the exterior surface. Matching grooves may also be fabricated
on the respective surface of the support element 168 to recess the
feed conductor flush with the surface if desired.
[0109] In a different embodiment (not shown), a portion of the feed
conductor 172 is routed along a lateral edge of the support element
178. To accommodate this implementation, the opening 194 is
fabricated closer to that lateral edge.
[0110] The radiating element 180 is affixed to the chassis via a
conductive sponge at the ground coupling point and to the feed
cable via a solder joint at the feed point. In one variant, both
couplings are effected via solder joints. Additionally or
alternatively, a suitable adhesive or mechanical retaining means
(e.g., snap fit, c-clip) may be used if desired.
[0111] The radiator cover 178 is, in the illustrated embodiment,
fabricated from any suitable dielectric material (e.g. plastic).
The radiator cover 178 is attached to the device housing by any of
a variety of suitable means, such as: adhesive, press-fit, snap-in
fit with support of additional retaining members 182, etc.
[0112] In a different construction (not shown), the radiator cover
178 comprises a non-conductive film, laminate, or non-conductive
paint bonded onto one or more of the exterior surfaces of the
respective radiator element.
[0113] In one embodiment, a thin layer of dielectric is placed
between the radiating element 180, the coaxial cable 172 and the
metal support 176 in order to prevent direct contact between the
radiator and metal carrier in all but one location: the ground
point. The insulator (not shown) has an opening that corresponds to
the location and size of the ground point on the radiator element
180, similarly to the embodiment described above with respect to
FIG. 1A.
[0114] The cover 178 is fabricated from a durable oxide or glass
(e.g. zirconia, or Gorilla.sup.s Glass manufactured by Dow Corning)
and is welded (i.e., via a ultrasonic-welding (USW) technique) onto
the device body. Other attachment methods are useable including but
not limited to adhesive, snap-fit, press-fit, heat staking,
etc.
[0115] Similarly to the prior embodiment of FIG. 1A, the antenna
radiator element 180, the feed conductor 172, the metal support
176, and the device enclosure cooperate to form a coupled loop
resonator, thereby facilitating formation of the chassis excited
antenna structure that is efficient, simple to manufacture and is
lower cost compared to the existing solutions.
[0116] As with exemplary antenna implementation described above
with respect to FIGS. 1A-1D, antenna performance for the device of
FIG. 1E is improved compared to the existing implementations,
largely because the radiator element is placed outside the metallic
enclosure/chassis, while still being coupled to the chassis.
Exemplary Mobile Device Configuration
[0117] Referring now to FIG. 2A, an exemplary embodiment 200 of a
mobile device comprising two antenna components configured in
accordance with the principles of the present invention is shown
and described. The mobile device comprises a metal enclosure (or
chassis) 202 having a width 204, a length 212, and a thickness
(height) 211. Two antenna elements 210, 230, configured similarly
to the embodiment of FIG. 1A, are disposed onto two opposing sides
106, 206 of the housing 202, respectively. Each antenna element is
configured to operate in a separate frequency band (e.g., one
antenna 210 in a lower frequency band, and one antenna 230 in an
upper frequency band, although it will be appreciated that less or
more and/or different bands may be formed based on varying
configurations and/or numbers of antenna elements). Other
configurations may be used consistent with the present invention,
and will be recognized by those of ordinary skill given the present
disclosure. For example, both antennas can be configured to operate
in the same frequency band, thereby providing diversity for MIMO
operations. In another embodiment, one antenna assembly is
configured to operate in an NFC-compliant frequency band, thereby
enabling short range data exchange during, e.g., payment
transactions.
[0118] The illustrated antenna assembly 210 comprises a rectangular
antenna radiator 108 disposed on the side 106 of the enclosure, and
coupled to the feed conductor 116 at a feed point (not shown). To
facilitate mounting of the radiator 108, a pattern 107 is
fabricated on the side 106 of the housing. The feed conductor 116
is fitted through an opening 114 fabricated in the housing side. A
portion of the feed conductor is routed along the side 106
lengthwise, and is coupled to the radiator element 108. An antenna
cover 118 is disposed directly on top of the radiator 108 so as to
provide isolation for the radiator.
[0119] The illustrated antenna assembly 230 comprises a rectangular
antenna radiator 238 disposed on the housing side 206 and coupled
to feed conductor 236 at a feed point (not shown). The feed
conductor 236 is fitted through an opening (not shown) fabricated
in the housing side 206. A portion of the feed conductor is routed
along the side 206 lengthwise, in a way that is similar to the feed
conductor 116, and is coupled to the radiator element 238 at a feed
point.
[0120] In one embodiment, the radiating elements 108, 238 are
affixed to the chassis via solder joints at the coupling points
(ground and feed. In one variant, the radiating elements are
affixed to the device via a conductive sponge at the ground
coupling point and to the feed cable via a solder joint at the feed
point. In another variant, both connections are effected via a
conductive sponge. Other electrical coupling methods are useable
with embodiments of the invention including, but not limited to,
c-clip, pogo pin, etc. Additionally, a suitable adhesive or
mechanical retaining means (e.g., snap fit) may be used if desired
to affix the radiating element to the device housing.
[0121] The cover elements 118, 240 are in this embodiment also
fabricated from any suitable dielectric material (e.g. plastic,
glass, zirconia) and are attached to the device housing by a
variety of suitable means, such as e.g., adhesive, press-fit,
snap-in with support of additional retaining members (not shown),
or the like. Alternatively, the covers may be fabricated from a
non-conductive film, or non-conductive paint bonded onto one or
more exterior surfaces of the radiator element(s) as discussed
supra.
[0122] A single, multi-feed transceiver may be used to provide feed
to both antennas. Alternatively, each antenna may utilize a
separate feed, wherein each antenna radiator directly is coupled to
a separate feed port of the mobile radio device via a separate feed
conductor (similar to that of the embodiment of FIG. 1A) so as to
enable operation of each antenna element in a separate frequency
band (e.g., lower band, upper band). The device housing/chassis 102
acts as a common ground for both antennas.
[0123] FIG. 2B shows another embodiment 250 of the mobile device of
the invention, wherein two antenna components 160, 258 are disposed
on top and bottom sides of the mobile device housing 102,
respectively. Each antenna component 160, 258 is configured
similarly to the antenna embodiment depicted in FIG. 1C, and
operates in a separate frequency band (e.g., antenna 160 in an
upper frequency band and antenna 258 in a lower frequency band). It
will further be appreciated that while the embodiments of FIGS. 2A
and 2B show two (2) radiating elements each, more radiating
elements may be used (such as for the provision of more than two
frequency bands, or to accommodate physical features or attributes
of the host device). For example, the two radiating elements of
each embodiment could be split into two sub-elements each (for a
total of four sub-elements), and/or radiating elements could be
placed both on the sides and on the top/bottom of the housing (in
effect, combining the embodiments of FIGS. 2A and 2B). Yet other
variants will be readily appreciated by those of ordinary skill
given the present disclosure.
[0124] In the embodiment of FIG. 2B, the antenna assemblies 160,
258 are specifically configured to fit in a substantially conformal
fashion onto a top or a bottom side of the device housing 252. As
the housing 252 comprises a sleeve-like shape, metal support
elements 168, 260 are provided. Support elements 168, 260 are
shaped to fit precisely into the openings of the housing, and are
attached to the housing via any suitable means, such as for example
press fit, micro-welding, adhesives, or fasteners (e.g., screws or
rivets). The outside surfaces of the support elements 168, 260 are
shaped receive the antenna radiators 180 and 268, respectively. The
support elements 168, 260 include openings 170, 264, respectively,
designed to fit the feed conductors 172, 262. The feed conductors
172, 262 are coupled to the main PCB 256 of the portable device.
The device display (not shown) is configured to fit within the
cavity 254 formed on the upper surface of the device housing.
Antenna cover elements 178, 266 are disposed above the radiators
180, 268 to provide isolation from the exterior influences. In
another implementation (not shown) the antenna elements
[0125] In one variant, the radiating elements 180, 268 are affixed
to the respective antenna support elements via solder joints at the
coupling points (ground and feed). In another variant, conductive
sponge and suitable adhesive or mechanical retaining means (e.g.,
snap fit, press fit) are used. 160, 258 are configured in a
non-conformal arrangement.
[0126] As described above, the cover elements 178, 266 may be
fabricated from any suitable dielectric material (e.g., plastic,
zirconia, or tough glass) and attached to the device housing by any
of a variety of suitable means, such as e.g., adhesives, press-fit,
snap-in with support of additional retaining members 182, 270,
272
[0127] In a different embodiment (not shown), a portion of the feed
conductor is routed along a lateral edge of the respective support
element (168, 268). To accommodate this implementation, opening
170, 264 are fabricated closer to that lateral edge.
[0128] The phone housing or chassis 252 acts as a common ground for
both antennas in the illustrated embodiment.
[0129] A third embodiment 280 of the mobile device is presented in
FIG. 2C, wherein the antenna assemblies 210, 290 are disposed on
the left and the bottom sides of the mobile device housing 202,
respectively. The device housing 202 comprises a metal enclosure
supporting one or more displays 254. Each antenna element of FIG.
2C is configured to operate in a separate frequency band (e.g.,
antenna 290 in a lower frequency band and antenna 210 in an upper
frequency band). Other configurations (e.g., more or less elements,
different placement or orientation, etc.) will be recognized by
those of ordinary skill given the present disclosure.
[0130] The antenna assemblies 210, 290 are constructed similarly to
the antenna assembly 210 described above with respect to FIG. 2A.
The device housing 202 of the exemplary implementation of FIG. 2C
is a metal enclosure with closed sides, therefore not requiring
additional support element(s) (e.g., 168) to mount the antenna
radiator(s).
[0131] In one embodiment, the lower frequency band (i.e., that
associated with one of the two radiating elements operating at
lower frequency) comprises a sub-GHz Global System for Mobile
Communications (GSM) band (e.g., GSM710, GSM750, GSM850, GSM810,
GSM900), while the higher band comprises a GSM1900, GSM1800, or
PCS-1900 frequency band (e.g., 1.8 or 1.9 GHz).
[0132] In another embodiment, the low or high band comprises the
Global Positioning System (GPS) frequency band, and the antenna is
used for receiving GPS position signals for decoding by e.g., an
internal GPS receiver. In one variant, a single upper band antenna
assembly operates in both the GPS and the Bluetooth frequency
bands.
[0133] In another variant, the high-band comprises a Wi-Fi (IEEE
Std. 802.11) or Bluetooth frequency band (e.g., approximately 2.4
GHz), and the lower band comprises GSM1900, GSM 1800, or PCS 1900
frequency band.
[0134] In another embodiment, two or more antennas, configured in
accordance with the principles of the present invention, operate in
the same frequency band thus providing, inter alia, diversity for
Multiple In Multiple Out (MIMO) or for Multiple In Single Out
(MISO) applications.
[0135] In yet another embodiment, one of the frequency bands
comprises a frequency band suitable for Near Field Communications
applications, e.g., ISM 13.56 MHz band.
[0136] Other embodiments of the invention configure the antenna
apparatus to cover LTE/LTE-A (e.g., 698 MHz-740 MHz, 900 MHz, 1800
MHz, and 2.5 GHz-2.6 GHz), WWAN (e.g., 824 MHz-960 MHz, and 1710
MHz-2170 MHz), and/or WiMAX (2.3, and 2.5 GHz) frequency bands.
[0137] In yet another diplexing implementation (not shown) a single
radiating element and a single feed are configured provide a single
feed solution that operates in two separate frequency bands.
Specifically, a single dual loop radiator forms both frequency
bands using a single fee point such that two feed lines
(transmission lines 128) of different lengths configured to form
two loops, which are joined together at a single diplexing point.
The diplexing point is, in turn, coupled to the port of the device
via a feed conductor 116.
[0138] As persons skilled in the art will appreciate, the frequency
band composition given above may be modified as required by the
particular application(s) desired. Moreover, the present invention
contemplates yet additional antenna structures within a common
device (e.g., tri-band or quad-band) with one, two, three, four, or
more separate antenna assemblies where sufficient space and
separation exists. Each individual antenna assembly can be further
configured to operate in one or more frequency bands. Therefore,
the number of antenna assemblies does not necessarily need to match
the number of frequency bands.
[0139] The invention further contemplates using additional antenna
elements for diversity/MIMO type of application. The location of
the secondary antenna(s) can be chosen to have the desired level of
pattern/polarization/spatial diversity. Alternatively, the antenna
of the present invention can be used in combination with one or
more other antenna types in a MIMO/SIMO configuration (i.e., a
heterogeneous MIMO or SIMO array having multiple different types of
antennas).
Business Considerations and Methods
[0140] An antenna assembly configured according to the exemplary
embodiments of FIGS. 1-2C can advantageously be used to enable
e.g., short-range communications in a portable wireless device,
such as so-called Near-Field Communications (NFC) applications. In
one embodiment, the NFC functionality is used to exchange data
during a contactless payment transaction. Any one of a plethora of
such transactions can be conducted in this manner, including e.g.,
purchasing a movie ticket or a snack; Wi-Fi access at an
NFC-enabled kiosk; downloading the URL for a movie trailer from a
DVD retail display; purchasing the movie through an NFC-enabled
set-top box in a premises environment; and/or purchasing a ticket
to an event through an NFC-enabled promotional poster. When an
NFC-enabled portable device is disposed proximate to a compliant
NFC reader apparatus, transaction data are exchanged via an
appropriate standard (e.g., ISO/IEC 18092/ECMA-340 standard and/or
ISO/ELEC 14443 proximity-card standard). In one exemplary
embodiment, the antenna assembly is configured so as to enable data
exchange over a desired distance; e.g., between 0.1 and 0.5 m.
Performance
[0141] Referring now to FIGS. 3 through 4, performance results
obtained during testing by the Assignee hereof of an exemplary
antenna apparatus constructed according invention are presented.
The exemplary antenna apparatus comprises separate lower band and
upper band antenna assemblies, which is suitable for a dual feed
front end. The lower band assembly is disposed along a bottom edge
of the device, and the upper band assembly is disposed along a top
edge of the device. The exemplary radiators each comprise a PCB
coupled to a coaxial feed, and a single ground point per
antenna.
[0142] FIG. 3 shows a plot of free-space return loss S11 (in dB) as
a function of frequency, measured with: (i) the lower-band antenna
component 258; and (ii) the upper-band antenna assembly 170,
constructed in accordance with the embodiment depicted in FIG. 2B.
Exemplary data for the lower (302) and the upper (304) frequency
bands show a characteristic resonance structure between 820 MHz and
960 MHz in the lower band, and between 1710 MHz and 2170 MHz for
the upper frequency band. Measurements of band-to-band isolation
(not shown) yield isolation values of about -21 dB in the lower
frequency band, and about -29 dB in the upper frequency band.
[0143] FIG. 4 presents data regarding measured free-space
efficiency for the same two antennas as described above with
respect to FIG. 3. The antenna efficiency (in dB) is defined as
decimal logarithm of a ratio of radiated and input power:
AntennaEfficiency = 10 log 10 ( Radiated Power Input Power ) Eqn .
( 1 ) ##EQU00001##
[0144] An efficiency of zero (0) dB corresponds to an ideal
theoretical radiator, wherein all of the input power is radiated in
the form of electromagnetic energy. The data in FIG. 4 demonstrate
that the lower-band antenna of the invention positioned at bottom
side of the portable device achieves a total efficiency (402)
between -4.5 and -3.75 dB over the exemplary frequency range
between 820 and 960 MHz. The upped band data (404) in FIG. 4,
obtained with the upper-band antenna positioned along the top-side
of the portable device, shows similar efficiency in the exemplary
frequency range between 1710 and 2150 MHz.
[0145] The exemplary antenna of FIG. 2B is configured to operate in
a lower exemplary frequency band from 700 MHz to 960 MHz, as well
as the higher exemplary frequency band from 1710 MHz to 2170 MHz.
This capability advantageously allows operation of a portable
computing device with a single antenna over several mobile
frequency bands such as GSM710, GSM750, GSM850, GSM810, GSM1900,
GSM1800, PCS-1900, as well as LTE/LTE-A and WiMAX (IEEE Std.
802.16) frequency bands. As persons skilled in the art appreciate,
the frequency band composition given above may be modified as
required by the particular application(s) desired, and additional
bands may be supported/used as well.
[0146] Advantageously, an antenna configuration that uses the
distributed antenna configuration as in the illustrated embodiments
described herein allows for optimization of antenna operation in
the lower frequency band independent of the upper band operation.
Furthermore, the use of coupled loop chassis excited antenna
structure reduces antenna size, particularly height, which in turn
allows for thinner portable communication devices. As previously
described, a reduction in thickness can be a critical attribute for
a mobile wireless device and its commercial popularity (even more
so than other dimensions in some cases), in that thickness can make
the difference between something fitting in a desired space (e.g.,
shirt pocket, travel bag side pocket, etc.) and not fitting.
[0147] Moreover, by fitting the antenna radiator(s) flush with the
housing side, a near `zero volume` antenna is created. At the same
time, antenna complexity and cost are reduced, while robustness and
repeatability of mobile device antenna manufacturing and operation
increase. The use of zirconia or tough glass materials for antenna
covers in certain embodiments described herein also provides for an
improved aesthetic appearance of the communications device and
allows for decorative post-processing processes.
[0148] Advantageously, a device that uses the antenna configuration
as in the illustrated embodiments described herein allows the use
of a fully metal enclosure (or metal chassis) if desired. Such
enclosures/chassis provide a robust support for the display
element, and create a device with a rigid mechanical construction
(while also improving antenna operation). These features enable
construction of thinner radio devices (compared to presently
available solutions, described above) with large displays using
fully metal enclosures.
[0149] Experimental results obtained by the Assignee hereof verify
a very good isolation (e.g., -21 dB) between an antenna operating
in a lower band (e.g., 850/900 MHz) and about -29 dB for an antenna
operating an upper band (1800/1900/2100 MHz) in an exemplary dual
feed configuration. The high isolation between the lower band and
the upper band antennas allows for a simplified filter design,
thereby also facilitating optimization of analog front end
electronics.
[0150] In an embodiment, several antennas constructed in accordance
with the principles of the present invention and operating in the
same frequency band are utilized to construct a multiple in
multiple out (MIMO) antenna apparatus.
[0151] It will be recognized that while certain aspects of the
invention are described in terms of a specific sequence of steps of
a method, these descriptions are only illustrative of the broader
methods of the invention, and may be modified as required by the
particular application. Certain steps may be rendered unnecessary
or optional under certain circumstances. Additionally, certain
steps or functionality may be added to the disclosed embodiments,
or the order of performance of two or more steps permuted. All such
variations are considered to be encompassed within the invention
disclosed and claimed herein.
[0152] While the above detailed description has shown, described,
and pointed out novel features of the invention as applied to
various embodiments, it will be understood that various omissions,
substitutions, and changes in the form and details of the device or
process illustrated may be made by those skilled in the art without
departing from the invention. The foregoing description is of the
best mode presently contemplated of carrying out the invention.
This description is in no way meant to be limiting, but rather
should be taken as illustrative of the general principles of the
invention. The scope of the invention should be determined with
reference to the claims.
* * * * *